Figure 3.

Fracture related problems and epitaxial structures. (a) Epitaxial grating on freestanding GaN membrane, and the inset is the zoom-in view of grating region; (b), (c) and (d) the resultant 700-nm period epitaxial gratings: (b) 500-nm-wide grating; (c) 350-nm-wide grating; (d) 250-nm-wide grating.